VSP and air at low speeds

[LaurenB]

I’ve been experimenting with my variable speed pump (just had a single speed previously and ran it 24hrs).

I’m seeing that at lower speeds (less than 2k rpm) a rather large air bubble will form in the pump basket lid. It basically fills the dome of the lid. The bubble disappears when I increase the speed. I’ve just been bleeding the tiny bit of air out of the filter once a day.

Is this normal? Can it damage the pump?

Thanks as always!

 

[Texas Splash]

Is this normal? Can it damage the pump?

Yes it's quite common in VSPs and no it's not a problem as long as the pump pot water level never drops dangerously low or losses prime. It shouldn't, but always something to watch.

 

[PoolStored]

Low RPM air is a conundrum of VSPs we don't have an answer for...tons of threads and back channel discussions...it's just a thing. We believe that the lower RPMs reduce the clamping force of the pump basket o-ring, allowing minute amounts of air in over time.

Clean the pump lid area where the o-ring sits with alcohol. Get a new o-ring for the pump lid and drain plugs. Use Magic Lube II (or other silicone LUBRICANT, not PTFE/Teflon. Clean the top of the volute VERY well with rubbing alcohol/denatured alcohol. I got some 3000 grit sandpaper and polished the top of my volute. My air bubble is now small enough that 15 minutes at high RPM once a day clears the air. I don't worry about it anymore.

How big is the bubble after 24 hours of running?

 

[1poolman1]

I’ve been experimenting with my variable speed pump (just had a single speed previously and ran it 24hrs).

I’m seeing that at lower speeds (less than 2k rpm) a rather large air bubble will form in the pump basket lid. It basically fills the dome of the lid. The bubble disappears when I increase the speed. I’ve just been bleeding the tiny bit of air out of the filter once a day.

Is this normal? Can it damage the pump?

Thanks as always!

No need to "bleed" air from the filter. All filters (except some sand filters, not yours) have an internal air relief. A little air in the filter won't harm anything nor interfere with filtration. After a while, it happens to virtually all pool systems and is nothing to worry about. If it makes you comfortable, go ahead, put it makes your pool less "troublefree."

 

[mas985]

From my experience, there are two ways that air can get into a pump basket at low speed.

1) On low speed, pump basket lids sometimes do not seal as well as high speed because of the design.

2) The pump basket is under lower pressure than atmospheric pressure which forces dissolved gases to come out of solution. However, this usually takes much longer than #1 to occur (hours vs minutes).